Note 8 - Employee Post-employment Benefits - Fair Values of Assets Held by the Retirement Plan by Asset Category (Details) - USD ($) $ in Thousands	Jun. 06, 2017	May 31, 2016
Fair value of plan assets as of measurement date	$ 6,126	$ 6,209
Total assets reported as of fiscal year end	6,126	6,209
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets as of measurement date	80	249
Total assets reported as of fiscal year end	80	249
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] | US-based Companies [Member]
Fair value of plan assets as of measurement date	2,677	2,561
Total assets reported as of fiscal year end	2,677	2,561
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member] | International-based Companies [Member]
Fair value of plan assets as of measurement date	1,175	1,222
Total assets reported as of fiscal year end	1,175	1,222
Fixed Income Securities [Member] | Fair Value, Inputs, Level 1 [Member] | As of Measurement Date [Member]
Fair value of plan assets as of measurement date	1,504	1,259
Total assets reported as of fiscal year end	1,504	1,259
Public Real Estate Investment Trusts [Member] | Fair Value, Inputs, Level 1 [Member] | As of Measurement Date [Member]
Fair value of plan assets as of measurement date		315
Total assets reported as of fiscal year end		315
Other Retirement Plan Assets [Member] | Fair Value, Inputs, Level 1 [Member] | As of Measurement Date [Member]
Fair value of plan assets as of measurement date	690	603
Total assets reported as of fiscal year end	$ 690	$ 603